2017 multi-school Just do it (Hdu 6129)

Question source

Multi-school 2017 Hdu 6129

Title

To an array arr (maximum 2E5 ), is given an operation determined arr each prefix and XOR, as a new arr .
Operate the maximum number of 1E9 , last asked arr array is valid

idea

• 1. M is so big, instinctively want to find the pattern ( I also found the wrong in the game... )

• 2. After the game, I played the table again and found the rule of 1-2-4-8 ( you will know when you hit the table to 8 )

• 3. Binary enumeration with 1e9 is enough for the law ( here is very similar to fast exponentiation )

• Pay attention to details when writing, easy to cross the boundary (code is as follows)

AC code

#include <set>
#include <map>
#include <queue>
#include <vector>
#include <cstdio>
#include <math.h>
#include <cstring>
#include <iostream>
#include <algorithm>

#define sc(x) scanf("%d",&x);
#define pr(x)  cout << x << endl;
#define bug(x)  cout << #x << " = " << x << endl;
#define ppr(x,y) cout << "(" << x << "," << y << ")" << endl;
#define mem(arr,x) memset(arr,x,sizeof arr);
#define clr(arr)   mem(arr,0);

using namespace std;
typedef long long LL;
typedef pair<int,int> P;
const int maxn = 2e5 + 5;
const int inf  = 0x3f3f3f3f;
const int mod  = 1e9 + 7;
int a[maxn];
int n,m;

void F(int x){      //m = x 时的变换 
    for(int i = x + 1; i <= n ; ++i)
        a[i] ^= a[i - x];
}

void _Bit(){        //用二进制枚举把m 分解成二进制乘积的变换 
    int x = 1;
    while(m){
        if(m & 1){
            F(x);
        }
        x *= 2;
        m >>= 1; 
    }   
}

int main(){
    ios::sync_with_stdio(false);
    int T;
    sc(T)
    while(T--){
        scanf("%d%d",&n,&m);
        for(int i = 1 ; i <= n ; i++) scanf("%d",a + i);
        _Bit(); 
        for(int i = 1;  i <= n ; i++) printf("%d%c",a[i],i == n ? '\n' : ' ');
    }
}